How to fix missing "use strict" error in JavaScript

A missing "use strict" error is common when you use ESLint. There are 2 possible fixes to it:

• add the statement “use strict” in double quotes as a first line in your JS file

  "use strict"
  //the rest of your JS code goes below
  // AND must be in a strict mode
  

• add a custom ESLint rule (as a comment!) to ignore the missing “use strict statement”

  /*eslint strict: ["error", "never"]*/
  
  //the rest of your JS code goes below
  //AND can be in a non-strict mode
  

You should try the first solution and if you’re not sure why it doesn’t work, then you can disable the ESLint errors for missing strict mode.